One type of drug delivery device known in the art is an injection-apparatus which contains a medical, therapeutic, diagnostic, pharmaceutical or cosmetic compound (drug) before it is administered to a patient, and which is used to administer the compound through the skin of the patient via a hollow needle. Injection apparatus of this type includes pre-filled syringes and autoinjectors.
A pre-filled syringe is a syringe which is filled with drug prior to distribution to the end user who will administer the drug to the patient. A pre-filled syringe typically includes a drug containment container forming part of a syringe body, a plunger for expelling the drug, and either an attached hypodermic needle or else features to allow a needle to be attached by the user prior to administration of the drug so that the drug can be delivered directly from the syringe in which it is supplied through the needle into the patient. The user of the syringe will typically need to be trained in the skill of administering injections, and may be the patient themselves, a doctor, a nurse or other carer such as a family member.
Autoinjectors are syringes that are used to reduce the skill needed to administer an injection compared with an ordinary, non-automatic pre-filled syringe. They are therefore more suitable than ordinary syringes for use by people who have not been trained in the skill of giving injections, and are often used to administer drugs for treating unplanned ‘crisis’ conditions such as anaphylactic shock or nerve gas poisoning where trained medical personnel may not be available. They are also used where it is advantageous for drugs to be administered in a home environment without the presence of trained medical personnel, for instance in the delivery of some drugs for treating cancer or auto-immune diseases. In this instance the person administering the drug may be the patient themselves or a family member who may have disabilities including limited strength, dexterity or vision.
Autoinjectors typically include a drug containment container along with a secondary structure which includes mechanisms to automatically insert a hypodermic needle into the patient and operate the plunger to administer the drug. This drug containment container is generally filled with drug in an aseptic environment and then assembled to the secondary structure after it has left this aseptic environment. In this way the risk of particulate and biological contamination of the drug by exposure to the secondary structure is reduced. Examples of this type of device include the EpiPen™ from King Pharmaceuticals and the DAI™ from Scandinavian Health Limited.
In a similar way pre-filled syringes may be assembled to additional structures outside the sterile filling environment after filling, such as needle safety mechanisms to prevent cross-contamination of blood borne diseases due to needle stick injuries after use.
These types of syringes are usually made from glass because glass provides various benefits. Glass has good resistance to moisture and gas permeation.
It has good transparency which allows the drug to be inspected after filling. It is also relatively inert to many drugs. However glass has several disadvantages including fragility and the ability to contaminate certain drugs.
An alternative group of materials, cyclic olefin polymers, have been used instead of glass as they typically have less of a contaminating effect on drugs and still exhibit good transparency. These materials include cyclic olefin copolymers such as Topas™ from Topas Advanced Polymers GmbH, and cyclic olefin homopolymers such as Crystal Zenith™ from Daikyo. However these materials do not have the same resistance to gas permeability as glass so can allow greater permeation of atmospheric gases such as oxygen through the container into the drug, where the gases can cause the drug to degrade.
Oxygen absorbing materials are known to be used in food and beverage packaging to reduce the oxygen levels within packaging. Typical oxygen absorbing materials include iron, low molecular weight organic compounds such as ascorbic acid and sodium ascorbate, and polymeric materials incorporating a resin and a catalyst.
Patent application US 2008/0072992 describes a drug container which may be made of cyclic olefin copolymer, and which is enclosed within a foil pouch in which the atmosphere between the container and the envelope wall is exposed to an oxygen-absorbing material. US 2003/0106824 A1 also describes a sealed package containing a medicament container and a gas absorbing component.
Both of the above described patent applications require a user to first remove the sealed envelope in order to access the drug. This arrangement has various disadvantages when used with prefilled syringes and autoinjectors:                it increases the number of steps needed for a user to administer the drug;        the envelope can obscure the drug during storage of the syringes or autoinjector making the drug more difficult or impossible to inspect for quality prior to use;        the envelope increases the size of the overall drug packaging;        there is a risk that the user will remove the drug container prematurely from the envelope causing the drug to be contaminated by oxygen, particularly if the user is not aware of the function and importance of the envelope in protecting the drug from oxygen;        users may find it difficult to open the envelope, particularly those users with physical or cognitive disabilities.        
There are also other issues which need to be considered when oxygen absorbers are used in conjunction with syringes or autoinjectors. It is necessary to prevent oxygen absorbers from absorbing excessive oxygen before they are assembled into the syringe or autoinjector so that they do not lose their efficacy. The oxygen absorber may also be a source of particulate, chemical or biological contamination and so may need to be isolated from the drug and drug delivery path.